1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly to a capacitor element for use in a peripheral circuit of a semiconductor device such as a non-volatile memory device and the like, which have a stacked gate structure and a multilayered electrode structure.
2. Description of the Related Art
Semiconductor devices (semiconductor chips) having a non-volatile memory cell such as an electrically programmable ROM (EPROM), an electrically erasable and programmable ROM (EEPROM), a flash memory and the like have a stacked gate structure having a floating gate electrode layer and a control gate electrode layer in their memory cell formation region. Moreover, on a substrate of each of these semiconductor devices, peripheral circuits such as a control circuit required for driving the memory cell are also formed together with the memory cells.
In a peripheral circuit region, there are provided thin film elements such as transistor elements, resistance elements, and capacitor elements, which are necessary for the respective peripheral circuits. These elements should be formed along with a memory cell portion for the sake of reducing burdens in processes.
For example, paying attention to a structure of a capacitor element used in the peripheral circuit, in a semiconductor device having a flash memory, a capacitor element which uses a layer forming a tunnel oxide film (first gate insulating film) as a charge storage layer has been heretofore formed, the tunnel oxide film being formed in a lower layer of a floating gate electrode layer. In this case, a layer forming the floating gate electrode layer and a semiconductor substrate have been used as a capacitor electrode.
However, a capacitor structure using a layer forming an inter-gate insulating film (second gate insulating film), which is formed between a floating gate electrode layer and a control gate electrode layer, as a charge storage layer of a capacitor element has been recently desired. This is because, since the inter-gate insulating film generally uses a higher dielectric material than the tunnel oxide film, a reduction in an area of the capacitor element can be more achieved when the inter-gate insulating film is used as the charge storage layer of the capacitor element.